The number of applications for equipment and systems that include the use of information processors such as computers, microprocessors, and central processing units continues to grow dramatically. In addition, there is continued growth in the use of these systems while operating on a substantially limited power supply such as batteries. There are applications in which the information processors require a precisely timed calibrated delay routine in which the power consumption is to be minimized.
Many microprocessors have two built-in clocks that typically use RC (resistor-capacitor) oscillators. One clock offers high accuracy at the expense of high power consumption. The high accuracy clock is typically used to time or schedule critical events. The other clock, which will be referred to as the watchdog timer, is a low power consumption clock, but it is typically very inaccurate. The watchdog timer is typically used to recover from software failures. An alternative solution is to use external components such as a quartz crystal to provide a calibrated delay timer for the information processor. The external components require more space and thus result in larger sizes for the equipment and systems that require the time delay capability.
There is a need for methods and apparatus that allow more efficient use of the available power for devices and systems that use information processors. Particularly, there is a need for methods that can provide accurately timed delays while using the available power for the timing function more efficiently than is possible with the standard technology.